Quantitation of the rat hippocampal capillaries in different regions wild at different postnatal ages was performed using computer-aided inorphometry based upon alkaline phosphatase histochemistry. Thirty-pteven rats aged 1, 3,5,7,10,14, and 21 days were used. With the aim of following the postnatal development of the hippocampal formation by qUMntitation of the capillaries in view of the regional variation in the development and structure of the hippocampus. The superiority of the alkaline phosphatase stained sections over yoiwentional histological preparations in revealing microvessels was ntteertained, as well as the optimization of the simultaneous azo dye coupling method in frozen sections for depicting microvascular profiles by using controlled fixation was described. As an effect of postnatal development on the hippocampal capillaries m decrease in the mean capillary diameter, a decrease in the mean inlercapillary distance, and an increase in the length density in all hlppocampal regions at the beginning of the second postnatal week were observed. The observed age and regional changes correlates with the metabolic activity, and cellular differentiation and development of each region at each postnatal age, which in turn reflects the increased capillarization at this age The mean intercapillary distance was considered as the best microvascular parameter in this study, with a relatively higher significance than the mean capillary diameter and the capillary length density Recommendations for future research have been suggested according to the results of current study.